Since decades the free-radical polymerization used in electrotechnics, electronics, dental industry, is combined with remarkable advantages in these fields. The frequently used acrylates and methacrylates are applied in combination with pigments and fillers or as pure polymerizable resins. It is well-known that during free-radical polymerization some side-reactions take place. One of them is the inhibition of the outer layer of the polymerizable material due to the influence of oxygen. The thickness of this layer depends on the viscosity of the polymerizable material, the degree of filling, the applied temperature and the time of polymerization. Frequently, the oxygen inhibited layer is disadvantageous due to the mechanical properties in this part are insufficient, the abrasion is higher and the toxicological/allergic potential is increased. The polymerization of very small layers is limited due to the oxygen inhibition, for example in case of covering electronic circuits by screen printing or for dental sealing materials or varnishes.
Furthermore, the conventional methacrylates that were used for dental applications are ester compound. Consequently, they hydrolysis under acidic or basic conditions that frequently leads to a long-term failure.
In order to reduce the oxygen inhibited layer different possibilities were suggested. One of them is the today well-known use of carbonyl/amine initiator systems for photochemical polymerization (R. S. Davison, J. W. Goodin, Eur.Polym.J 18 (1982) 597). Dekker used special color initiators that change triplet-oxygen into singulet-oxygen (C. Dekker, Makromol. Chem. 180 (1979) 2027). Furthermore, surface active additives were used (C. R. Morgan, A. D. Ketley, J. Radiat.Curing 7 (1980) 10) or the photochemical SH-En-Addition was applied (C. R. Morgan, F. Magnotta, A. D. Ketley, J.Polym.Sci., Polym. Ed. 15 (1977), 627).
The photochemical polymerization of monoacrylamides was studied by Smets (G. Smets, Bull.Soc.Chim.Belges 71 (1962) 857, G. Oster, J.Amer.Chem.Soc. 79 (1957) 595). A large number of bisacrylamides were described by Ferrutti (P. Ferrutti et al., Polymer 26 (1985) 1336). These bisacrylamides are solids that are soluble in water due to the secondary amide group or they comprises a piperidine group.
A combination of free-radical and Michael addition polymerization was suggest for encapsulation of electronic circuits (DD 295645; invs.: J. Klee, H.-H. Hxc3x6rhold, I. Scherlitz-Hofmann).
The new synthesized bisacrylamides should be liquids in order to polymerized them without of solvents and furthermore they and the resulting polymers should be insoluble in water.